Bump @microsoft/typespec-msgraph in /additions (#936)

Bumps [@microsoft/typespec-msgraph](https://github.com/microsoftgraph/typespec-msgraph) from 1.0.0-Preview.3 to 1.0.0-Preview.4.
- [Commits](https://github.com/microsoftgraph/typespec-msgraph/commits)

---
updated-dependencies:
- dependency-name: "@microsoft/typespec-msgraph"
  dependency-version: 1.0.0-Preview.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]